std::ranges::iota_view<W, Bound>::size - cppreference.com (original) (raw)

| constexpr auto size() const requires (std::same_as<W, Bound> && /*advanceable*/<W>) || (/*is-integer-like*/<W> && /*is-integer-like*/<Bound>) | | std::sized_sentinel_for<Bound, W>; | | (since C++20) | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------- | | ------------- |

Returns the size of the view if the view is bounded.

For the definitions of /*advanceable*/ and /*is-integer-like*/, see _[advanceable](iterator.html#advanceable "cpp/ranges/iota view/iterator")_ and is-integer-like respectively.

[edit] Return value

If any of W and Bound is not a integer-like type, returns _[to-unsigned-like](../../ranges.html#to-unsigned-like "cpp/ranges")_ (_[bound](../iota%5Fview.html#bound "cpp/ranges/iota view")_ - _[value](../iota%5Fview.html#value "cpp/ranges/iota view")_ ).

Otherwise, returns (_[value](../iota%5Fview.html#value "cpp/ranges/iota view")_ < 0) ?
( (_[bound](../iota%5Fview.html#bound "cpp/ranges/iota view")_ < 0) ?
`_[to-unsigned-like](../../ranges.html#to-unsigned-like "cpp/ranges")_` (\-`_[value](../iota%5Fview.html#value "cpp/ranges/iota view")_` ) \-` ` `_[to-unsigned-like](../../ranges.html#to-unsigned-like "cpp/ranges")_` (\-`_[bound](../iota%5Fview.html#bound "cpp/ranges/iota view")_` ) : _[to-unsigned-like](../../ranges.html#to-unsigned-like "cpp/ranges")_ (_[bound](../iota%5Fview.html#bound "cpp/ranges/iota view")_ ) + _[to-unsigned-like](../../ranges.html#to-unsigned-like "cpp/ranges")_ (-_[value](../iota%5Fview.html#value "cpp/ranges/iota view")_ )
) : _[to-unsigned-like](../../ranges.html#to-unsigned-like "cpp/ranges")_ (_[bound](../iota%5Fview.html#bound "cpp/ranges/iota view")_ ) - _[to-unsigned-like](../../ranges.html#to-unsigned-like "cpp/ranges")_ (_[value](../iota%5Fview.html#value "cpp/ranges/iota view")_ ) .

[edit] Example

#include #include   int main() { unsigned initial_value{1}, bound{5}; auto i{std::views::iota(initial_value, bound)}; assert(i.size() == bound - initial_value and i.size() == 4);   auto u{std::views::iota(8)}; // assert(u.size()); // Error: size() is not present since “u” is unbounded }

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also

| | returns an integer equal to the size of a range(customization point object)[edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | returns a signed integer equal to the size of a range(customization point object)[edit] |